When she was a toddler, my eldest started to get very curious about pebbles, leaves, sticks, and any other small natural object that she could find. She would pick them up and put them into her diaper (I had forgotten this, but her dad reminded me of it the other night). Then when she got a little older, she would use one of her socks like a bag–she’d carry it around and put the little objects into it (I do remember this).
When she got a little older, she became interested in insects. We even had some preying mantises but I don’t remember how we obtained them. I think we ordered them through the mail? Not sure. But those were cool. We had all sorts of animals actually. She always liked the natural sciences.